氮气退火对氟化非晶碳膜结构和电学性能的影响

采用电子回旋共振等离子体化学气相淀积(ECR-CVD)方法以C4F8和CH4为源气体制备了氟化非晶碳(a-C:F)膜并在氮气气氛中对a-C:F膜进行了退火处理研究.X光电子能谱(XPS)化学结构分析表明,退火后a-C:F膜中CF3,CF2和CF含量减少,而C-CFx(x=1～3)交联结构增多.电学性能研究指出,退火后a-C:F薄膜的介电常数由于电子极化和薄膜密度的增大而上升,Al/a-C:F/Si结构的阻滞效应由于界面态密度下降而减弱,同时a-C:F膜的π-π*带隙和电荷陷阱能量减小并导致薄膜漏电流增大.     

退火温度对DLC膜热稳定性及摩擦学性能的影响

采用非平衡磁控溅射技术分别在氮化硅陶瓷球和高速工具钢圆盘表面制备了类金刚石(DLC)膜。使用箱式电阻炉对DLC膜在大气环境中进行高温退火处理以研究环境温度对DLC膜摩擦学性能的影响;并分别采用激光拉曼光谱仪和球-盘式摩擦磨损试验机对退火处理前后DLC膜的结构和摩擦学性能进行了研究。采用金相显微镜观察了摩擦副磨损表面的形貌。研究发现,随着退火温度的升高,DLC膜中sp3杂化键向sp2杂化键的转化加快,当退火温度为600℃时,DLC膜发生严重的石墨化。而当退火温度为400℃时,DLC膜的摩擦系数及磨损率最小。拉曼测试表明400℃退火处理后DLC膜表层含有Si及SiO2,在摩擦过程中形成了含SiC的转移膜,使得DLC膜的摩擦系数明显降低,磨损减小。研究结果表明,退火处理对DLC膜的热稳定性和摩擦学性能有重要的影响。     

锌膜氧化制备氧化锌薄膜的紫光发射

通过锌膜在金属锌熔点(419℃)以上温度和50Pa的氧气压力下退火氧化的方法制备ZnO薄膜,研究了退火温度对ZnO薄膜组织结构及发光性能的影响.ZnO薄膜的室温光致发光谱是由发光中心在424nm处的单一紫光组成.随着退火温度的升高,紫光的强度增加,当温度超过600℃时紫光的强度反而降低.在50Pa氧气压力下,紫光的发射归因于电子从价带到锌间隙原子(Zni)缺陷之间的跃迁.     

ECR-CVD制备氟化非晶碳低k介质薄膜

采用电子回旋共振等离子体化学气相沉积(ECR-CVD)方法,以C4F8和CH4为源气体在不同气体流量比R(R=[CH4]/{[CH4] [C4F8]})条件下成功地沉积了氟化非晶碳(a-C:F)低介电常数(低k)材料.采用X光电子能谱和椭圆光谱方法分析了a-C:F薄膜的化学组分和光学性质.沉积的a-C:F薄膜介电常数约为2.1～2.4,热稳定性优于350℃.随着气体流量比的增大,沉积a-C:F薄膜中的碳含量增大,CF、CF2、CF3含量减少,C-C交链成分增加,从而使得π-π(*)吸收增强,并引起薄膜光学带隙下降.氮气气氛下350℃温度退火后应力释放引起a-C:F薄膜厚度变化,变化量小于4%.450℃温度退火后,由于热分解作用薄膜厚度变化量在30%左右.     

退火温度对W-DLC薄膜结构与摩擦学性能的影响

采用矩形气体离子源复合磁控溅射技术制备W掺杂的类金刚石薄膜,研究了大气下室温到500℃对薄膜结构稳定性及摩擦学性能的影响。利用扫描电镜、X射线衍射仪、拉曼光谱仪、三维表面轮廓仪分析了薄膜的微观结构,采用摩擦磨损试验仪分析了薄膜的摩擦学性能。结果表明,室温下薄膜结构致密,主要由非晶碳中弥散分布纳米晶WC1-x相组成,薄膜具有良好的耐磨性能。当退火温度达到300℃以上时薄膜发生了氧化,并发生石墨化转变,磨损率增加。随着退火温度进一步升高,薄膜氧化严重,摩擦系数升高,耐磨性能降低,500℃时薄膜已完全失效。     

高温退火对反应溅射制备的a-SiC:H薄膜结构的影响

通过红外透射谱、拉曼散射谱和X射线衍射谱的测量,研究了反应溅射制备的氢化非晶硅碳膜（SP-a-SiC：H）高温退人处理后的结构变化。发现在等时退火的情况下,退火温度对薄膜结构影响明显,H原子的逸出温度与键合有关,H从CH_n中逸出要比从SiH_n键中追出需要更高的温度,样品经800℃退火后,a－SiC：H膜转化为μc－SiC膜     

退火预处理对中空纤维炭膜结构和性能的影响

炭膜具有优异的热稳定性、化学稳定性和气体分离性能.以聚酰亚胺中空纤维膜为前驱体，经过T_g附近退火预处理(250、300和350℃),进而高温炭化制备高性能中空纤维炭膜，研究了预处理条件对炭膜结构和气体分离性能的影响.结果表明，当退火预处理温度升高时，中空纤维炭膜的结构更加致密，其CO₂/CH₄和H₂/CH₄选择性提高，气体通量下降.尤其是当退火预处理温度为350℃时，与未经预处理的中空纤维炭膜相比，其CO₂/CH₄和H₂/CH₄选择性分别提高了98%和195%.同时，研究了渗透温度和压力对气体分离性能的影响，采用HIM(氦离子电镜)、FTIR和XRD对中空纤维炭膜的结构进行了表征.     

真空下载荷对a-C:H超润滑薄膜的摩擦学性能影响研究

高含H量a-C:H薄膜因能在宏观尺度实现超润滑(μ0.01)而备受关注,具有广阔的应用前景。但高含H量a-C:H薄膜的摩擦学特性对测试条件十分敏感,为此,本文研究了典型工况(载荷)对薄膜摩擦学特性的影响及其摩擦学机制。采用球盘摩擦实验机对a-C:H薄膜在不同载荷下进行摩擦实验;使用表面轮廓仪观测薄膜在不同工况下的磨损形貌,计算磨损率;使用拉曼光谱仪测试摩擦界面处碳相结构信息及H元素的相对含量。结果表明:随着载荷的增加,摩擦界面处sp~3键向sp~2键转化程度增加,sp~2键石墨化程度增加;摩擦界面处H元素的消耗速率增加,消耗的不均匀性同时增加;在超润滑阶段,摩擦因数基本不受载荷影响,薄膜的耐磨性能依赖于超润滑状态带来的超低摩擦因数,不同载荷下薄膜均没有明显磨损;超出超润滑阶段后,薄膜均出现较严重磨损。     

类金刚石薄膜的耐热性研究进展

类金刚石薄膜具有良好的物理化学性能、光电性能、机械性能及摩擦学性能。但是在高于400℃的温度条件下，DLC膜易向石墨结构转变，从而阻碍了其在高温条件下的应用。因此关于类金刚石薄膜耐热性的研究是目前的一个热门研究课题。在综合分析近年来该领域研究的基础上总结了影响DLC膜耐热性的3种因素：膜结构、掺杂、制备方法，并分析了各种因素的影响机理。     

气体分离复合膜的聚丙烯腈支撑底膜的制备与表征

采用相转化法,以聚丙烯腈聚合物为制膜材料,研究了聚合物的浓度、凝胶浴温度、挥发时间及各种添加剂对膜结构和性能的影响.采用扫描电子显微镜、凝胶渗透色谱等手段对底膜进行了表征.结果表明,采用增加聚合物的浓度、降低凝胶浴温度或加长挥发时间,以及在一定范围内增加添加剂H2O、ZnCl2和正丁醇含量等方法,都可以明显改变膜性能,使膜断面由大空腔结构趋向海绵孔结构.制备了具有海绵孔断面结构的,用作气体分离复合膜底膜的PAN超滤膜.     

Effect of deposition temperature and thermal annealing on the dry etch rate of a-C: H films for the dry etch hard process of semiconductor devices

The effect of deposition and thermal annealing temperatures on the dry etch rate of a-C:H films was investigated to increase our fundamental understanding of the relationship between thermal annealing and dry etch rate and to obtain a low dry etch rate hard mask. The hydrocarbon contents and hydrogen concentration were decreased with increasing deposition and annealing temperatures. The I(D)/I(G) intensity ratio and extinction coefficient of the a-C:H films were increased with increasing deposition and annealing temperatures because of the increase of sp² bonds in the a-C:H films. There was no relationship between the density of the unpaired electrons and the deposition temperature, or between the density of the unpaired electrons and the annealing temperature. However, the thermally annealed a-C:H films had fewer unpaired electrons compared with the as-deposited ones. Transmission electron microscopy analysis showed the absence of any crystallographic change after thermal annealing. The density of the as-deposited films was increased with increasing deposition temperature. The density of the 600 °C annealed a-C:H films deposited under 450 °C was decreased but at 550 °C was increased, and the density of all 800 °C annealed films was increased. The dry etch rate of the as-deposited a-C:H films was negatively correlated with the deposition temperature. The dry etch rate of the 600 °C annealed a-C:H films deposited at 350 °C and 450 °C was faster than that of the as-deposited film and that of the 800 °C annealed a-C:H films deposited at 350 °C and 450 °C was 17% faster than that of the as-deposited film. However, the dry etch rate of the 550 °C deposited a-C:H film was decreased after annealing at 600 °C and 800 °C. The dry etch rate of the as-deposited films was decreased with increasing density but that of the annealed a-C:H films was not. These results indicated that the dry etch rate of a-C:H films for dry etch hard masks can be further decreased by thermal annealing of the high density, as-deposited a-C:H films. Furthermore, not only the density itself but also the variation of density with thermal annealing need to be elucidated in order to understand the dry etch properties of annealed a-C:H films.     

Effects of annealing temperature on the optical, bonding, structural and electrical properties of nitrogenated amorphous carbon thin films grown by surface wave microwave plasma chemical vapor deposition

We have studied the effects of annealing temperature (AT) on the properties of nitrogenated amorphous carbon (a-C:N) films grown at room temperature (RT) on quartz substrates by surface wave microwave plasma chemical vapor deposition (SWMP-CVD) using camphor alcohol gas as carbon plasma sources. The thickness, optical, bonding, structural and electrical properties of the as-grown (RT) and anneal-treated in range from 100 to 500°C of a-C:N films were measured and compared. The film thickness is decreased rapidly with increasing AT above 350°C. The wide range of optical absorption characteristics is observed depending on the AT. The optical band gap of as-grown a-C:N films is approximately 2.8 eV, gradually decreased to 2.5 eV for the films anneal-treated at 300°C and beyond that it decreased rapidly up to 0.9 eV at 500°C . Visible-Raman Spectroscopy (Raman) revealed the amorphous structure of as-grown a-C:N films and, the growth of nanocrystallinity of a-C:N films upon increase of AT. Raman and Fourier transform infrared spectroscopy (FTIR) analyses respectively shown the structural and composition of the films can be tuned by optimizing the AT. The change of optical, bonding, structural and electrical properties of SWMP-CVD grown a-C:N films with higher AT was attributed due to the fundamental changes in the bonding and band structure of the a-C:N films.     

Adherent amorphous hydrogenated carbon films on metals deposited by plasma enhanced chemical vapor deposition

This paper reports the findings of a study of the structural, mechanical, and tribological properties of amorphous hydrogenated carbon (a-C:H) coatings for industrial applications. These thin films have proven quite advantageous in many tribological applications, but for others, thicker films are required. In this study, in order to overcome the high residual stress and low adherence of a-C:H films on metal substrates, a thin amorphous silicon interlayer was deposited as an interface. Amorphous silicon and a-C:H films were grown by using a radio frequency plasma enhanced chemical vapor deposition system at 13.56 MHz in silane and methane atmospheres, respectively. The X-ray photoelectron spectroscopy technique was employed to analyze the chemical bonding within the interfaces. The chemical composition and atomic density of the a-C:H films were determined by ion beam analysis. The film microstructure was studied by means of Raman scattering spectroscopy. The total stress was determined through the measurement of the substrate curvature, using a profilometer, while micro-indentation experiments helped determine the films' hardness. The friction coefficient and critical load were evaluated by using a tribometer. The results showed that the use of the amorphous silicon interlayer improved the a-C:H film deposition onto metal substrates, producing good adhesion, low compressive stress, and a high degree of hardness. SiC was observed in the interface between the amorphous silicon and a-C:H films. The composition, the microstructure, the mechanical and tribological properties of the films were strongly dependent on the self-bias voltages. The tests confirmed the importance of the intensity of ion bombardment during film growth on the mechanical and tribological properties of the films.     

Preparation of various DLC films by T-shaped filtered arc deposition and the effect of heat treatment on film properties

Different types of diamond-like carbon (DLC) films (ta-C, a-C, ta-C:H and a-C:H) were prepared on super hard alloy (WC-Co) substrate using a T-shape filtered arc deposition (T-FAD) system. At first, the film properties, such as structure, hydrogen content, density, hardness, elastic modulus, were measured. Ta-C prepared with a DC bias of −100 V showed the highest density (3.1 g/cm³) and hardness (70-80 GPa), and the lowest hydrogen content (less than 0.1 at. %). It was found that the hardness of the DLC film is proportional to approximately the third power of film density. The DLC films were then heated for 60 min in an electric furnace at 550 °C in N₂. Only the ta-C film hardly change its structure, although other films were graphitized. The 200-nm thick ta-C film was then heated for 60 min through the temperature range from 400 to 800 °C in N₂ with 2 vol.% of O₂ and the film structure found to be stable up to 700 °C. The substrate was oxidized at 800 °C, indicating the ta-C film had a thermal barrier function up to that temperature.     

Dielectric response and structure of amorphous hydrogenated carbon films with nitrogen admixture

The optical properties and structure of a-C:H films were modified by addition of nitrogen into the CH₄/H₂ deposition mixture. Three films prepared in capacitively coupled rf discharge were compared: (a) hydrogenated diamond like carbon film with hydrogen content of 34% and indentation hardness of 21.7 GPa, (b) hard a-C:H:N film with nitrogen content of 13% and indentation hardness of 18.5 GPa and (c) soft a-C:H:N film with nitrogen content of 10% and indentation hardness of 6.7 GPa. It is shown how the parametrized density of states model describing dielectric response of electronic interband transitions can be applied to modified a-C:H:N and how it can be combined with correct treatment of transmittance measured in infrared range using additional Gaussian peaks in joint density of phonon states. This analysis resulted in determination of film dielectric function in wide spectral range (0.045-30 eV) and provided also information about the density of states of valence and conduction bands and lattice vibrations.     

Formation of nano-columnar amorphous carbon films via electron beam irradiation

Electrical beam (EB) irradiation is used to chemically modify the amorphous carbon film, a-C:H, which is prepared by the DC magnetron sputtering. The starting a-C:H film has vague columnar structure with lower density intercolumns as predicted by Thornton structure model. The EB-irradiated a-C:H film has fine nano-columnar structure with the average columnar size of 10–15 nm. This size is equivalent to the measured in-plain correlation length by the Raman spectroscopy. Little change in the sp2/sp3 bonding ratio is observed in the columnar matrix before and after EB-irradiation. Increase of sp2/sp3 ratio is noted in the intercolumns of irradiated a-C:H films. No change is detected in the hydrogen content of a-C:H films before and after EB-irradiation: 35 at% hydrogen in a-C:H. Increase of the in-plain density via EB-irradiation, is attributed to the increase of local atomic density in the intercolumns, which is measured by the electron energy zero-loss spectroscopy. This local densification is accompanied with ordering or graphitization in the intercolumns of the EB-irradiated a-C:H film. The nano-columnar a-C:H film modified by EB-irradiation has non-linear elasticity where indentation displacement should be reversible up to 8% of film thickness. Owing to this ordering and densification via EB-irradiation, softening both in stiffness and hardness takes place with increasing the irradiation time.     

阴极真空弧源沉积氟化类金刚石薄膜的结构与性能研究

采用脉冲磁过滤阴极真空弧源沉积系统(FCVA)在单晶硅基片上制备了含氟量不同的一系列氟化类金刚石膜(a-C:F).重点研究了氟掺杂对非晶态碳基薄膜结构、机械性能和疏水性能的影响.薄膜的成分和结构采用X射线光电子能谱仪(XPS)和激光拉曼光谱(Raman)进行了表征,薄膜表面形貌和粗糙度采用原子力显微镜(AFM)进行了分析.使用纳米压痕仪测量了薄膜硬度,纳米划痕仪测量了膜基结合力.采用躺滴法测量薄膜与双蒸水之间的接触角来评价其疏水性能.结果表明,随着CF4流量的逐渐增加,薄膜的氟化程度逐渐增强,膜中最大氟含量达45.6 at%;薄膜呈典型的类金刚石状结构,但薄膜的无序化程度增强;由于-CFn+的刻蚀,薄膜表面更加致密化、粗糙度逐渐减小.薄膜的机械性能良好,硬度在12GPa以上.薄膜的疏水性能得到增强,与双蒸水之间的最大接触角达106°,接近于聚四氟乙烯(PTFE,110°).     

Mechanical properties of a-C:H and a-C:H/SiOx nanocomposite thin films prepared by ion-assisted plasma-enhanced chemical vapor deposition

a-C:H and a-C:H/SiO_x nanocomposite thin films were deposited on silicon, aluminum and polyimide substrates at 25 °C in an asymmetric 13.56 MHz r.f.-driven plasma reactor under heavy ion bombardment. Fourier transform infrared spectra of the films indicate that the nanocomposite filmsappears to consist of an atomic scale random network of a-C:H and SiO_x. Raman spectroscopy revealed that the sp² carbon fraction in the nanocomposite film was reduced compared with the a-C:H film. The intrinsic stress of both films increased with increasing negative bias voltage (−V_dc) at the substrate. However, the nanocomposite films exhibited lower intrinsic stress compared w with a-C:H-only films. Especially, a thin SiO_x-rich interlayer was very effective in reducing the film stress and enhancing the bonding strength at the interface. The interlayer allowed deposition of thick films of up to 5 μm. Also, the nanocomposite films were stable in 0.1 M NaOH solution and showed good microhardness.     

Effects of applied substrate bias during reactive sputter deposition of nanocomposite tantalum carbide/amorphous hydrocarbon thin films

Nanocomposite tantalum carbide/amorphous hydrocarbon (TaC/a-C:H) thin film composition, structure, and mechanical properties depend on the direct current bias voltage (V_b) level applied to the substrate during reactive sputter deposition. A set of TaC/a-C:H films was deposited across the range V_b = 0 to − 300 V with all other deposition parameters held constant except substrate temperature, which was allowed to reach its steady state during the depositions. Effects of V_b on film composition and structure were explored, including TaC crystallite size and dispersion using X-ray diffraction and high resolution transmission electron microscopy. In addition, the dependency of stress and hardness on V_b was studied with an emphasis on relationships to a-C:H phase structure.     

退火温度对CsI(Tl)薄膜微观结构和闪烁性能的影响

采用真空热蒸发法制备了CsI(Tl)薄膜, 然后进行了不同温度的真空热处理．用X射线衍射仪、扫描电子显微镜、X射线荧光光谱仪及正电子寿命谱仪对CsI(Tl)薄膜样品进行了分析, 并测得了样品的光产额．结果表明, 该CsI(Tl)薄膜沿(200)晶面择优取向生长．经过较低温度退火, CsI薄膜中的Tl⁺离子向薄膜表面扩散, 薄膜中缺陷数量增加, 且尺寸较大, 光产额略微增高．经过250℃退火, 薄膜中低温退火所形成缺陷得到恢复, 薄膜缺陷尺寸变小, 且数目减少, 具有较好的结晶状态, 光产额提高．经过400℃退火, 薄膜结构发生显著变化, 薄膜中缺陷大幅增加, 结晶状态变差, Ti+含量减少, 光产额急剧下降．